The present invention is in the technical field of system-reliability monitoring and predictive evaluation. In other words, the present invention is in the technical field of predictive identification of system reliability problems and/or system failure.
U.S. Pat. No. 5,014,220, issued May 7, 1991, McMann et al., (the '220 patent") is directed to a method for generating reliability models for fault-tolerant systems in which the interrelationships between components are too complex to model. The '220 patent defines reliability analysis as the analysis of events that contribute to the occurrence of undesirable conditions, and the application of probability theory to determine that the likelihood of these conditions falls within acceptable limits. The invention of the '220 patent is a reliability-model generator which automatically generates a composite reliability model for a complex system. The reliability model generated then can be analyzed by existing reliability analysis tools. Described therein is a prior art evaluation tool entitled SURE that computes the upper and lower bounds on system reliability given the initial state and those states that represent an unreliable system. According to the '220 patent, the use of SURE will require excessive computing resources to solve and validate a model for a complex system if the model encompasses excessive state/space relationships. The invention of the '220 patent is a system for aggregating a plurality of low-level reliability models into a single reliability model based upon definitions of interrelationships of the low level models.
U.S. Pat. No. 5,377,112, issued Dec. 27, 1994, Brown, Jr. et al., is directed to an engine diagnostic method in which the differences between actual and model conditions of a plurality of operating parameters are used for diagnosis. The data falls into one of the fault regions if there are significant discrepancies between the modeled and actual values.
U.S. Pat. No. 5,399,961, issued Mar. 21, 1995, Wild et al., is directed to a system for monitoring the performance of an oxygen probe of a catalytic converter, in which the performance loss is deemed impermissible when a certain mean value drops below a threshold value. The mean value is a time-dependent mean value. The measure of the sought-after mean value is the ratio of (1) the number of scanning values within a pre-given range, to (2) the total number of scannings.
U.S. Pat. No. 5,523,701, issued Jun. 4, 1996, Smith et al., is directed to diagnostic and monitoring systems which use the frequency of a motor's current to judge machine operation based on the background noise of the current spectrum.
U.S. Pat. No. 5,561,610, issued Oct. 1, 1996, Schricker et al., is directed to a system in which the slope (of a graph of values) and duration of a parameter having a value that is dependent upon machine performance is determined, and a warning is given when the level is greater than a threshold. The purpose of the system is to predict failures using a warning threshold that is a function of duration and slope of the condition. The fault would be signaled when either the slope value or duration value is too high.
U.S. Pat. No. 5,566,091, issued Oct. 15, 1996, Schricker et al., is directed to a method for diagnosing and predicting component failure by monitoring similar machine components in parallel to produce trend information. The trend in the differences between a plurality of parallel components is determined and recorded and this historical information is employed to track future component performance.
U.S. Pat. No. 5,581,694, issued Dec. 3, 1996, Iverson et al., is directed to a method for predicting failures in electronic and mechanical systems that have a plurality of interconnected units. The method integrates the operating data of the separate units.
U.S. Pat. No. 5,608,338, issued Mar. 4, 1997, Maeda, is directed to a method for determining the life or reliability of a "thin film transistor" ("TFT") that factors in variations when a plurality of TFT's are manufactured under the same conditions.